Crucial role for Ca2+/calmodulin-dependent protein kinase-II in regulating diastolic stress of normal and failing hearts via titin phosphorylation

• Verfasst von: Hamdani, Nazha [VerfasserIn]
• Verfasst von: Kreußer, Michael [VerfasserIn]
• Verfasst von: Backs, Johannes [VerfasserIn]
• Titel: Crucial role for Ca2+/calmodulin-dependent protein kinase-II in regulating diastolic stress of normal and failing hearts via titin phosphorylation
• Verf.angabe: Nazha Hamdani, Judith Krysiak, Michael M. Kreusser, Stefan Neef, Cristobal G. dos Remedios, Lars S. Maier, Markus Krüger, Johannes Backs, Wolfgang A. Linke
• E-Jahr: 2013
• Jahr: 2 Jan 2013
• Umfang: 11 S.
• Fussnoten: Im Titel ist "2+" hochgestellt ; Gesehen am 25.02.2021
• Titel Quelle: Enthalten in: Circulation research
• Ort Quelle: New York, NY : Assoc., 1953
• Jahr Quelle: 2013
• Band/Heft Quelle: 112(2013), 4, Seite 664-674
• ISSN Quelle: 1524-4571
• DOI: doi:10.1161/CIRCRESAHA.111.300105
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1749263793

Abstract

Rationale:Myocardial diastolic stiffness and cardiomyocyte passive force (Fpassive) depend in part on titin isoform composition and phosphorylation. Ca2+/calmodulin-dependent protein kinase-II (CaMKII) phosphorylates ion channels, Ca2+-handling proteins, and chromatin-modifying enzymes in the heart, but has not been known to target titin.Objective:To elucidate whether CaMKII phosphorylates titin and modulates Fpassive in normal and failing myocardium.Methods and Results:Titin phosphorylation was assessed in CaMKIIδ/γ double-knockout (DKO) mouse, transgenic CaMKIIδC-overexpressing mouse, and human hearts, by Pro-Q-Diamond/Sypro-Ruby staining, autoradiography, and immunoblotting using phosphoserine-specific titin-antibodies. CaMKII-dependent site-specific titin phosphorylation was quantified in vivo by mass spectrometry using stable isotope labeling by amino acids in cell culture mouse heart mixed with wild-type (WT) or DKO heart. Fpassive of single permeabilized cardiomyocytes was recorded before and after CaMKII-administration. All-titin phosphorylation was reduced by >50% in DKO but increased by up to ≈100% in transgenic versus WT hearts. Conserved CaMKII-dependent phosphosites were identified within the PEVK-domain of titin by quantitative mass spectrometry and confirmed in recombinant human PEVK-fragments. CaMKII also phosphorylated the cardiac titin N2B-unique sequence. Phosphorylation at specific PEVK/titin N2B-unique sequence sites was decreased in DKO and amplified in transgenic versus WT hearts. Fpassive was elevated in DKO and reduced in transgenic compared with WT cardiomyocytes. CaMKII-administration lowered Fpassive of WT and DKO cardiomyocytes, an effect blunted by titin antibody pretreatment. Human end-stage failing hearts revealed higher CaMKII expression/activity and phosphorylation at PEVK/titin N2B-unique sequence sites than nonfailing donor hearts.Conclusions:CaMKII phosphorylates the titin springs at conserved serines/threonines, thereby lowering Fpassive. Deranged CaMKII-dependent titin phosphorylation occurs in heart failure and contributes to altered diastolic stress.